To explore the relationship between family functioning, psychological capital, life history strategy, and relapse tendency of individuals with drug addiction, 842 individuals with drug addiction completed a questionnaire. The results showed that (1) there was a significant negative correlation between the family functioning of individuals with drug addiction and their relapse tendency; (2) psychological capital played an intermediary role between family functioning and relapse tendency; and (3) life history strategy regulated the mediating effect of psychological capital. The results of this study suggest that family members should collaborate with drug addiction treatment centers and participate in the education and treatment process to help reduce drug relapse tendency. Increasing the psychological capital and self-efficacy of individuals with drug addiction through group psychological counseling and psychological education courses could also reduce drug relapse tendency.